This invention relates to current-reducing devices and especially to modifiable-conductive-state, thin foil devices.
The need for fuses which rapidly interrupt the flow of current in a circuit when the current rises above a given value and the present scientific interest in high-power electrical pulses with energy greater than 10 megajoules has led to research in inductive storage systems. In such systems, electrical energy is stored in an inductor, L, thru which current is flowing. The energy is switched into a load by opening a switch in series with the inductor. This interruption in current causes the inductor to generate a voltage which appears across the switch. The switch must be able to withstand very high inductive voltages to rapidly dissipate the energy in the inductor.
Opening switches commonly employed consist of a metallic wire or a file-type fuse. When sufficient energy is dissipated in the fuse, it explodes and its resistance can increase by many orders of magnitude (preferably, the resistance becomes infinite). This change in the electrical resistance of the fuse causes the desired current discontinuity.
However, these fuses act comparatively slowly and tend to ionize upon vaporization, which results in a restrike. The present invention greatly increase the speed of operation of a foil fuse and eliminates or greatly decreases the possibility of restrike. It also permits the generation of higher inductive voltages across the fuse.